Quarter	Millions of US Dollars
1997-01-01	229
1997-04-01	229
1997-07-01	229
1997-10-01	229
1998-01-01	229
1998-04-01	229
1998-07-01	229
1998-10-01	229
1999-01-01	229
1999-04-01	229
1999-07-01	229
1999-10-01	229
2000-01-01	229
2000-04-01	229
2000-07-01	229
2000-10-01	229
2001-01-01	229
2001-04-01	229
2001-07-01	229
2001-10-01	229
2002-01-01	225
2002-04-01	225
2002-07-01	222
2002-10-01	222
2003-01-01	217
2003-04-01	217
2003-07-01	213
2003-10-01	213
2004-01-01	208
2004-04-01	208
2004-07-01	204
2004-10-01	204
2005-01-01	199
2005-04-01	199
2005-07-01	194
2005-10-01	371
2006-01-01	369
2006-04-01	378
2006-07-01	371
2006-10-01	378
2007-01-01	374
2007-04-01	376
2007-07-01	380
2007-10-01	388
2008-01-01	394
2008-04-01	393
2008-07-01	361
2008-10-01	355
2009-01-01	330
2009-04-01	342
2009-07-01	590
2009-10-01	583
2010-01-01	536
2010-04-01	497
2010-07-01	526
2010-10-01	517
2011-01-01	524
2011-04-01	532
2011-07-01	480
2011-10-01	462
2012-01-01	455
2012-04-01	430
2012-07-01	420
2012-10-01	429
2013-01-01	192
2013-04-01	196
2013-07-01	203
2013-10-01	207
2014-01-01	207
2014-04-01	205
2014-07-01	818
2014-10-01	789
2015-01-01	699
2015-04-01	727
2015-07-01	728
2015-10-01	838
2016-01-01	877
2016-04-01	855
2016-07-01	1362
2016-10-01	1286
2017-01-01	1304
2017-04-01	1392
2017-07-01	1440
2017-10-01	1463
2018-01-01	2119
2018-04-01	2005